Metamath Proof Explorer


Theorem 1iscard

Description: 1 is a cardinal number. (Contributed by RP, 1-Oct-2023)

Ref Expression
Assertion 1iscard 1𝑜rancard

Proof

Step Hyp Ref Expression
1 omssrncard ωrancard
2 1onn 1𝑜ω
3 1 2 sselii 1𝑜rancard